<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#div1{
	width:100px;
	height:100px;
	border:1px #666666 solid;
     }
.box{background:#F00;}
</style>
<script>

function toRed()
{
	var oDiv=document.getElementById('div1')
	oDiv.className='box'
};
function toGreen()
{
	var oDiv=document.getElementById('div1')
	oDiv.style.background='green'
};
</script>
</head>

<body>

<input type="button" value="变红" onclick="toRed()" />
<input type="button" value="变绿" onclick="toGreen()" />
<div id="div1"></div>
</body>
</html>
